49-Mile Drive Free. This planned driving route through San Francisco takes a minimum of three hours and hits most of the high points. It is marked by signs and features a blue line in the middle of the road. The route begins at Civic Center and ends at the airport. For a free map, contact the San Francisco Travel Association. or get more information here.

GoCar Rentals Departs from Fisherman's Wharf and Union Square. Fee. The world’s first computer-guided storytelling cars, these open-air, three-wheel vehicles with a motorcycle engine guide passengers to the city’s sights. They tell you when to turn, where to turn, and if the car is in the wrong lane. And they are so much fun, this really is the only way to go. Made in Holland, each seats two and can go up to 35 m.p.h., though under 30 feels best. The onboard Global Positioning System provides a custom narration leading drivers on either, or both, of two routes--the waterfront/Golden Gate Park or downtown/Union Square--explaining the sights along the way. The sporty cars can be parked in any legal motorcycle or car parking spot, allowing time for exploration or a snack. Typical rentals last about 2 hours. However, because the price per hour goes down every hour, it makes sense to rent it for the whole day and pack in a lot of sightseeing. The itinerary is available in five languages (English, French, German, Spanish, and Italian).

Mr. Toad's Vintage Car Tours Departs from Fisherman’s Wharf. Fee. This family-owned and -operated sightseeing company features brand-new, environmentally friendly, custom-built pre-1930s vehicles. They include a 1929 Model A "woody," a 1912 Rambler, and a 1925 Yellowstone bus. Choose from an 80-minute "Hop Around the City" tour, or a 2.5-hour “Postcard San Francisco” tour that makes four or five stops. Why the name? The owner says, “Thanks to our propane-powered engines, our vehicles have 60% fewer ozone-forming emissions than gasoline. We figure that toads are green, and so are we!”